Temp.hs

{-|
This module provides functions greating a temporary postgres instance on a random port for testing.

 @
 result <- 'start' []
 case result of
   Left err -> print err
   Right tempDB -> do
      -- Do stuff
      'stop' tempDB
 @

The are few different methods for starting @postgres@ which provide different
methods of dealing with @stdout@ and @stderr@.

The start methods use a config based on the one used by [pg_tmp](http://ephemeralpg.org/), but can be overriden
by in different values to the first argument of the start functions.

-}
{-# LANGUAGE RecordWildCards, LambdaCase, ScopedTypeVariables #-}
module Database.Postgres.Temp
  ( -- * Types
    DB (..)
  , StartError (..)
  -- * Starting @postgres@
  -- $options
  , start
  , startAndLogToTmp
  , startWithHandles
  -- * Stopping @postgres@
  , stop
  ) where
import Database.Postgres.Temp.Internal

{- $options
'startWithHandles' is the most general way to start postgres. It allows the user to
pass in it's own handles for @stdout@ and @stderr@. 'start' and 'startAndLogToTmp'
both call 'startWithHandles' passing in different handles. 'start' uses the current
process's @stdout@ and @stderr@ and 'startAndLogToTmp' logs to files in the 'mainDir'.

@postgres@ is started with a default config with the following options:

 @
   listen_addresses = ''
   shared_buffers = 12MB
   fsync = off
   synchronous_commit = off
   full_page_writes = off
   log_min_duration_statement = 0
   log_connections = on
   log_disconnections = on
   unix_socket_directories = {mainDir}
   client_min_messages = ERROR
 @

 Any of the options can be overriden by passing in a different value when starting

 @
   Right db <- 'start' [("log_min_duration_statement", "1000")]
 @

-}